Fan blade sign display device

ABSTRACT

A fan blade sign display device includes a rotary device, an actuator adapted to rotate the rotary device, a display unit installed in the rotary device, and a control device adapted to turn on/off the display unit. A sign is appeared in the movement path of the LED array upon rotation of the LED array with the rotary device at the speed in which the motion cycle of the LED array is smaller than the transient retention time of visual sensation when controlling the control device to turn on/off the display unit.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to electric fans and, more particularly, to a fan blade sign display device, which comprises a display unit installed in the fan blade to show a sign upon rotary motion of the fan blade.

[0002] Electric fans are intensively used in summer to cause currents of air for cooling or ventilating. Because electric fans are inexpensive, household products distributors tend to use electric fans as gifts to attract consumers. A regular electric fan is comprised of a fan motor, and a fan blade coupled to the output shaft of the fan motor. When switched on the fan motor, the fan blade is rotated to cause currents of air. Because the speed of revolution of the fan blade is high, it must be kept away from touch of the hands. Therefore, regular electric fans commonly have a grilled cover for protection. Nowadays, the fan blades of electric fans are commonly injection-molded from plastics. In order to attract the consumers, fan blade may be made transparent. However, a child may not know the rotation status of the transparent fan blade of an electric fan during its operation. When a child inserts the fingers into the grilled cover of an electric fan by mistake during rotation of the fan blade, the fingers will be cut or severely injured by the fan blade.

SUMMARY OF THE INVENTION

[0003] It is one object of the present invention to provide a fan blade sign display device, which gives a warning sign upon rotary motion of the fan blade, preventing children from touching the fan blade. It is another object of the present invention to provide a fan blade sign display device, which produces a visual display signal for advertising upon rotary motion of the fan blade. To achieve these and other objects of the present invention, the fan blade sign display device comprises a rotary device, for example, the fan blade of an electric fan, an actuator, for example, a fan motor adapted to rotate the rotary device, a display unit installed in the rotary device, and a control device adapted to turn on/off the display unit. A sign is appeared in the movement path of the LED array upon rotation of the LED array with the rotary device at the speed in which the motion cycle of the LED array is smaller than the transient retention time of visual sensation when controlling the control device to turn on/off the display unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]FIG. 1 is a front plain view showing an LED array installed in a fan blade according to the present invention.

[0005]FIG. 2 is a speed control block diagram of the present invention.

[0006]FIG. 3 is a block diagram of the LED array control circuit according to the present invention.

[0007]FIG. 4 is a circuit diagram of the present invention.

[0008]FIG. 5 is a LED array control time series diagram according to the present invention.

[0009]FIG. 6 is a schematic drawing showing an application example of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0010] Referring to FIG. 1, a fan blade sign display device 1 is installed in an electric fan's movable part (the blade) 2. When the activator (fan motor) 3 rotates the movable part 2, the fan blade sign display device 1 drives the LED array 13 thereof to flash, producing visual signal. Due to the effect of transient retention of visual sensation, the sign of the visual signal is retained in the human brain for about 40 ms. Therefore, the viewer sees a continuous stable sign displayed on the movable part 2.

[0011] Referring to FIGS. from 2 through 6, the fan blade sign display device 1 is comprised of a power supply unit 11, a driving unit 12, the aforesaid LED array 13, and the aforesaid actuator 3. The power supply unit 11 comprises a speed stabilizing circuit 111 adapted to control the speed of revolution of the actuator 3 at a predetermined constant level, causing a sign to be appeared in the movement path of the LED array 13 upon rotation of the LED array 13 with the movable part 2.

[0012] The driving unit 12 has software adapted to turn on/off the LED array 13 and to drive the LED array 13 to flash.

[0013] The design of the LED array may be variously embodied. In an example of the present invention, the LED array 13 is comprised of seven LEDs adapted to show the sign of “E” upon rotary motion of the movable part 2, and the speed of revolution of the actuator 3 is 2400 runs/minute. We decompose the sign into dot matrix, i.e., the sign “E” is a 5*7 standard dot matrix “E”. Because the speed of revolution of the actuator 3 is 2400 runs/minute, it takes 25 ms per run. If we divide one run into 72 dots, one run can display 12 letters (72/(5+1)) maximum, in which the pitch is one dot, and it takes 374 us to light up every dot. The control sequence of the seven LEDs to show the sign of “E” is as shown in FIG. 5.

[0014] By means of the transient retention effect of visual sensation, the sign is temporarily kept in the brain for about 40 ms. A continuous and stable picture is seen in the movement path of the LED array 13 upon rotation of the LED array 13 with the movable part 2 in case the motion cycle time of the LED array 13 is shorter than the visual retention time.

[0015] Further, the sign can be a company logo, trademark, warning letters or sign to keep children from touching the fan blade.

[0016] A prototype of fan blade sign display device has been constructed with the features of FIGS. 1˜6. The fan blade sign display device functions smoothly to provide all of the features discussed earlier.

[0017] Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

What the invention claimed is:
 1. A fan blade sign display device comprising: a rotary device; an actuator adapted to rotate said rotary device; a display unit installed in said rotary device; and a control device adapted to turn on/off said display unit; wherein a sign is appeared in the movement path of said LED array upon rotation of said LED array with said rotary device at the speed in which the motion cycle of said LED array is smaller than the transient retention time of visual sensation when controlling said control device to turn on/off said display unit.
 2. The fan blade sign display device as claimed in claim 1 wherein said actuator is a motor.
 3. The fan blade sign display device as claimed in claim 1 wherein said rotary device is a fan blade.
 4. The fan blade sign display device as claimed in claim 1 wherein said display unit is comprised of a LED (light emitting diode) array.
 5. The fan blade sign display device as claimed in claim 1 wherein said control device is comprised of a power supply unit and a driving unit.
 6. The fan blade sign display device as claimed in claim 5 wherein said power supply unit comprises a speed stabilizing circuit adapted to control the speed of revolution of said rotary device.
 7. The fan blade sign display device as claimed in claim 1 wherein said driving unit comprises software adapted to control on/off of said display unit. 